Mitt Romney picked up two conservative endorsements Sunday to add to victories in three states last week heading into Super Tuesday, the biggest single day of the Republican presidential campaign.

With two days before contests in 10 states will decide how more than 400 delegates get allocated, Romney's three opponents all appeared on Sunday talk shows to outline how they can catch the front-running former Massachusetts governor.

Romney's victories Tuesday in Michigan and Arizona, followed by Saturday's triumph in the Washington state caucuses, gave him 207 delegates so far, according to CNN's unofficial estimate.

Former Pennsylvania Sen. Rick Santorum is next with 86, followed by Texas Rep. Ron Paul at 46 and former House Speaker Newt Gingrich trailing with 39. It takes 1,144 delegates to secure the Republican nomination to take on President Barack Obama in November.

In Saturday's Washington contest, Romney led with 38% to 25% for Paul, 24% for Santorum and 10% for Gingrich.

On Sunday, House Majority Leader Eric Cantor, R-Virginia, and Republican Sen. Tom Coburn of Oklahoma -- both noted conservatives -- endorsed Romney's presidential bid. The backing from Coburn and Cantor, a tea party favorite, could give Romney a boost among right-wing voters who so far have questioned his conservative credentials.

"What Romney has done in his 25 years in the private sector is precisely what we need a president to do in Washington," Coburn wrote in an op-ed in the Oklahoman newspaper. "Romney has done hard things. He has turned businesses around, told people hard truths about what needed to be done, inspired confidence and overcome excuses. Romney is not a career politician or a career legislator. As a former governor and business leader, he is an executive who knows how to use executive power."

Cantor's Virginia and Coburn's Oklahoma are two of the 10 Super Tuesday states on March 6. They will hold primaries, along with Ohio, Georgia, Tennessee, Vermont and Massachusetts. Three other states -- Idaho, North Dakota and Alaska -- are holding caucuses that day.

While Romney approached Super Tuesday riding high, Gingrich was in the most precarious position, needing a victory in Georgia to keep his campaign alive. Polls show him with a solid lead in the state he represented in Congress, and Gingrich spoke confidently Sunday about the road ahead.

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Appearing on CNN's "State of the Union," Gingrich pointed to the Gallup daily tracking poll, which has shown his support rising nationally in recent days to approach Santorum's second-place standing behind Romney, with Paul in fourth.

His strategy has been to conserve resources until Georgia, where he leads the polls, and try to attract support in other traditionally conservative Southern states to blunt Romney's momentum and outduel Santorum for right-wing votes.

"We have had a steady closing in the Gallup poll between Santorum and me every single week now for the last two weeks," Gingrich said. He told the ABC program "This Week with George Stephanopoulos" that "I think I'll win Georgia by a much, much bigger margin than Romney won Michigan."

"We're going to go on. We're competing in Tennessee, in Ohio, in Oklahoma, in a number of other states. We'll pick up delegates in a number of places," Gingrich said on ABC. "Then I think the following week, we're going to win Alabama and Mississippi, and we're going to be very competitive in Kansas."

However, late polls show Romney and Santorum statistically tied at the top in Tennessee and Ohio, and Gingrich didn't make the ballot in Virginia, another Super Tuesday state, limiting his opportunity to gain ground.

Santorum also failed to get on the Virginia ballot, and on "Fox News Sunday," he downplayed his chances of winning Ohio's key primary Tuesday, saying it was "a tough state for us only because of the money disadvantage."

In addition, Santorum's campaign was unable to meet eligibility requirements in some Ohio districts -- putting any delegates he wins in them in jeopardy.

Santorum also cited the continuing battle with Gingrich for conservative support in the race against the more moderate Romney.

"It's always harder when you've got two conservative candidates out there running in the race," Santorum said.

In such a situation, Santorum said, his ability to finish first or second in the upcoming primaries and caucuses will eventually narrow the field to a one-on-one race against Romney.

Paul told the CBS program "Face the Nation" that he was targeting the Super Tuesday caucus states of Alaska, Idaho and North Dakota in his quest for delegates despite being the only surviving candidate without a primary victory so far.

He and Romney are the only candidates on the Virginia ballot, and the polls show Romney far ahead. Asked if he was running to win the nomination or simply secure enough ballots to be a force at the Republican convention in August, Paul said his goal was both.

"I don't know why there has to be an either-or," Paul said. "If you're in a race to make a point or promote a cause, the best way to do that is to win."

On CNN, Gingrich said that despite Obama's improving favorability ratings, Republicans were still poised to take the White House and the Senate in November.

"People take stock," Gingrich said. "The price of gasoline is becoming a genuine crisis for many American families. If it continues to go higher it will crater the economy by August. People will have no discretionary income. As a result the president will go into the fall with very expensive gasoline, a weakening economy, a disastrously bad policy in the Middle East. I think that's a pretty big burden."

Romney, campaigning in Cincinnati, also took aim at Obama and Democratic polices that he said spend "massively more than what we take in" to burden future generations with debt.

He sounded perplexed over the liberal voting record of college students, saying, "I don't know why any college student in America doesn't vote for a Republican."

"How they can vote for people that put these burdens on them, I'll never know," Romney said.

Santorum, meanwhile, backtracked from his criticism of Obama's call for higher education for all.

The candidate recently accused Obama of snobbery for advocating that all students attend college, saying not everyone would benefit from four years at what he called liberal-leaning university campuses.

However, when confronted by "Fox News Sunday" with Obama's past statements calling for different kinds of higher education options -- including community college or technical training programs -- Santorum said that made sense.

His motivation in criticizing Obama was to "focus not just on four-year college degrees," Santorum said. Asked why he thought Obama was only pushing a four-year program, Santorum said "maybe I was reading some things" that gave that impression.

"If it was in error, then I agree with the president that we should have options for people to go to variety of different training options for them," Santorum said.

On Friday, Santorum called his accusation that Obama was a snob a "little over the top."

"It was a strong term, probably not the smartest thing, but you know what, I don't give prepared talking points speeches written by other people," Santorum said in an interview on CNN's "The Situation Room with Wolf Blitzer." "I got a little passionate there and I used a harsher word than I normally would but the point was government shouldn't be dictating to people what they do."